A device of this type is described in British Patent GB 1 603 648, in the form of an electronic meter for measuring electrical power, having connection terminals for connection to an electrical power network and which includes a power measuring circuit constituted by an integrated circuit whose input terminals are connected to said connection terminals.
As shown in the figures of that patent relating to its various modes of connection, such a meter clearly has to be adapted to the type of power network in which it is to be connected.
In general, devices including electronic circuits for measuring one or more electrical parameters are traditionally designed to operate in only one mode of connection and run the risk, if they are used in any other way, of providing no signal, or only giving false measurements, or even being destroyed.
A problem arises in particular when a device of the type defined in the introduction needs to be capable of connection to an electrical network equally well by N+1 connection terminals or N+2 connection terminals, that is to say with possible use of an additional connection terminal, when the first terminal and the additional terminal can either be at the same potential or at two different potentials, whose difference represents a parasitic voltage, and when nevertheless the measuring circuit should not make any significant response to such a parasitic voltage.
In this context the present invention has as its main object the provision of a solution to this first problem.